1. Field of the Invention
The present invention relates to a cooling water circulating structure in an internal combustion engine.
2. Description of Background Art
A conventional cooling water circulating structure in a multi-cylinder type internal combustion engine is illustrated in FIG. 11. FIG. 11 illustrates a cooling water circulating structure as disclosed in JP-A No. H3-225015.
An internal combustion engine 01 is provided with a cooling water inlet 02a in one side face of a cylinder block 02 and a cooling water outlet 03a in a side face of a cylinder head 03 on the side opposite to the cooling water inlet 02a. Cooling water which has been fed, by means of a cooling water pump 04, to the cooling water inlet 02a formed in one side face of the internal combustion engine 01 passes through a water jacket 02b provided within the cylinder block 02 and flows into a water jacket 03b provided within the cylinder head 03, then flows out from the cooling water outlet 03a formed in the other side face of the internal combustion engine 01 to cool both cylinder block 02 and cylinder head 03.
The cooling water flowing out from the cooling water outlet 03a in the cylinder head 03 and having a high temperature is conducted to a radiator 05, in which it is cooled, then the cooling water thus cooled flows again into the internal combustion engine 01. Generally, such a cooling water circulating route as described above is concentional.
A review of the cooling water flow from the cooling water inlet 02a to the cooling water outlet 03a in the internal combustion engine 01 shows that the cooling water easily flows into a cooling water path which is close to a straight line L joining the cooling water inlet 02a and the cooling water outlet 03a and that running water in a cooling water flow path away from the straight line L becomes less powerful and this phenomenon is more conspicuous as the distance from the straight line L becomes longer, thus making the cooling water difficult to flow.
It follows that the cooling water outlet 03a side of the cylinder block 02 and the cooling water inlet 02a side of the cylinder head 03 are inferior in cooling effect as compared with a central portion and the portion around the central portion.
Moreover, since the cooling water inlet 02a and the cooling water outlet 03a in the internal combustion engine 01 are provided in side faces opposite to each other, it is not easy to effect the layout of the water piping.
In the foregoing JP-A No. H3-225015 there is described an example in which a cooling water flow path in the cylinder block and a cooling water flow path in the cylinder head are separated from each other. In this example, however, a pair of cooling water inlet and cooling water outlet are formed in each of the cylinder block and the cylinder head and in side faces opposite to each other, with the result that water piping becomes complicated and the layout thereof becomes more difficult.
The present invention has been accomplished in view of the above-mentioned point and it is an object of the invention to provide a cooling water circulating structure in an internal combustion engine wherein cooling water reaches every corner through a cylinder block and a cylinder head without being localized, thereby permitting efficient cooling of the whole, and which permits easy layout of water piping.
For achieving the above-mentioned object, according to a first embodiment of the invention, there is provided a cooling water circulating structure in an internal combustion engine wherein a cooling water inlet and a cooling water outlet are formed side by side in a side face of a cylinder block and a side face of a cylinder head, respectively, in a multi-cylinder type internal combustion engine, both the side faces lying on the same side of the internal combustion engine close to a water pump, and a cylinder block-side water jacket and a cylinder head-side water jacket are communicated with each other through a communication path formed on the side opposite to the side close to the water pump, thereby allowing cooling water to circulate.
Cooling water admitted from the cooling water inlet flows through the cylinder block-side water jacket (or the cylinder head-side water jacket) from one side to the opposite side, then on the opposite side the cooling water passes through the communication path and flows into the cylinder head-side water jacket (or the cylinder block-side water jacket), and flows through the cylinder head-side water jacket (or the cylinder block-side water jacket) toward the one side.
Thus, the cooling water reaches every corner in both cylinder block and cylinder head-side water jackets without being localized, thereby permitting efficient cooling of the whole.
Besides, since the cooling water inlet and outlet are provided on the same side close to a water pump, the layout of water piping is easy.
According to a second embodiment of the invention, there is provided, in combination with the first aspect, a cooling water circulating structure in an internal combustion engine wherein cylinders arranged in a crank shaft direction of the multi-cylinder type internal combustion engine are largely tilted forward, and the cooling water outlet is formed in a corner portion located at the highest position of the cylinder head-side water jacket.
When the cooling water admitted into the cylinder head-side water jacket (or the cylinder block-side water jacket from the communication path flows toward the cooling water outlet located on the opposite side, since the cooling water outlet lies in the highest corner portion of the cylinder head-side water jacket (or the cylinder block-side water jacket), the cooling water prevails substantially throughout the whole of the interior of the cylinder head-side water jacket (or the cylinder block-side water jacket) and thereafter flows out from the cooling water outlet which is located at a high position, whereby the whole of the cylinder head (or the cylinder block) can be cooled efficiently.
According to a third embodiment of the invention, there is provided, in combination with the first and second aspects, a cooling water circulating structure in an internal combustion engine wherein at least one of the cylinder block-side water jacket and the cylinder head-side water jacket is provided with a flow controlling wall which conducts cooling water substantially in a crank shaft direction.
By disposing the flow controlling wall at an appropriate position it is possible to conduct the cooling up to a portion in the water jacket concerned where the cooling water is difficult to prevail and hence possible to prevent localizing of the cooling water, thus permitting the whole of the internal combustion engine to be cooled efficiently.
Besides, the rigidity of the cylinder head or the cylinder block can be enhanced by the flow controlling wall.
According to a fourth embodiment of the invention there is provided, in combination with any of the first to third aspects, a cooling water circulating structure in an internal combustion engine wherein an auxiliary communication path for communication between the cylinder block-side water jacket and the cylinder head-side water jacket is provided separately from the foregoing communication path.
By disposing the auxiliary communication path in a portion within the water jacket located on the cooling water influent side from the communication path in which portion the cooling water is difficult to prevail or apt to stay, it is possible to let the cooling water reach every corner in the water jacket smoothly and hence possible to effect efficient cooling of the whole.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.